http://imgur.com/GeFv5ea

George,

I've got a 67 Grand Prix with a factory ammeter in the dash. I'd like to upgrade my system from an external voltage regulator to a 12SI 3 wire system. The current voltage regulator has two wires connected to it per the attached drawing.
Should the voltage sensing wire go from the new alternator #2 terminal to a connection between the ammeter and the battery or should the voltage sensing wire be connected to the junction block?
I'm planning on installing relays for the headlights. Should the new headlight voltage source come from a connection between the battery and the ammeter?

Thanks very much

Rick